The present invention is directed to bicycle braking devices and, more particularly, to a cantilever brake having brake shoes attached to adjustable links so that the lateral position of the brake shoes may be adjusted.
Cantilever style brakes are often used on mountain bikes and occasionally on road bikes to provide stronger braking force per unit of force applied to the brake lever than that provided by conventional caliper style brakes. A cantilever brake ordinarily comprises a pair of opposed brake arm assemblies, wherein each brake arm assembly includes a brake arm having an upper portion and a lower portion. A brake shoe is disposed on an intermediate portion of each brake arm such that the brake shoes face each other. The lower portion of each brake arm is pivotally attached to the bicycle frame, and a brake control cable coupling assembly is disposed on the upper portion of each brake arm. In one type of cantilever brake the upper portion of each brake arm is angled outwardly from the wheel rim and the brake is operated by pulling generally upwardly on a brake control cable wire attached to the cable coupling assembly of each brake arm. In another type of cantilever brake the brake arms are essentially straight. In this case an outer casing of the brake control cable is attached to the brake control cable coupling assembly of one brake arm and an inner wire of the brake control cable is attached to the brake control cable coupling assembly of the other brake arm. This type of brake is very efficient because the force of the brake control cable is applied substantially perpendicular to each brake arm.
With either type of cantilever brake, it is desirable to apply the force of the brake control cable as perpendicular to the brake arms as possible when the brake shoes are in the vicinity of the wheel rim to maximize the braking force per unit of force applied to the brake lever. Also, it is desirable to have the brake shoe oriented perpendicular to the rim sidewall when the brake shoe contacts the rim. Brake arm assemblies are designed with those goals in mind. However, brake arm assemblies designed for mountain bikes, for example, often are not optimized for use on road bikes because mountain bikes have relatively wide wheel rims, whereas road bikes have relatively narrow wheel rims. As a result, brake arm assemblies designed for mountain bikes will angle too far inwardly before the brake shoe contacts the rim of a road bike. Conversely, a brake arm assembly designed for road bikes will be angled too far outwardly when the brake shoe contacts the rim of a mountain bike. As a result, different brake shoe assemblies must be designed for different bicycles if optimum performance is desired. This increases design, tooling and manufacturing costs for the manufacturer and inventory costs for the dealer, and it prevents the bicyclist from using one type of brake arm assembly with different style bicycles.